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6.04.2016

Astronomers take first look beneath Jupiter’s clouds

Using radio waves and the Very Large Array (VLA) telescopes in New Mexico, researchers at the University of California, Berkeley and an international team of colleagues have managed to peek beneath the cloud tops on Jupiter and take a close look at the planet’s atmosphere.

As the researchers reported in Friday’s edition of the journal Science, they were able to conduct observations as deep as 60 miles (100 kilometers) beneath the cloud tops. They found several hot spots, regions that contain no clouds or condensable gases, and complex upwellings of ammonia in the part of Jupiter’s atmosphere beneath what’s visible to the human eye.

“We in essence created a three-dimensional picture of ammonia gas in Jupiter’s atmosphere, which reveals upward and downward motions within the turbulent atmosphere,” lead author and UC Berkley astronomy professor Imke de Pater explained in a statement. She and her colleagues hope that by studying these regions of Jupiter’s atmosphere, they will be able to determine how the planet’s intense internal heat source powers global circulation and cloud formation.

Since the ammonia gas partially absorbs the planet’s thermal radio emissions, the study authors were able to determine how much ammonia exists in the atmosphere and at what altitude it tends to be present. The resulting 3D map is said to resemble visible-light images captured by amateur astronomers, as well as those produced by the Hubble Space Telescope, de Pater added.

Credit: AAAS

Swirling ammonia upwellings among the Berkeley team’s discoveries

Co-author Michael Wong, also an astronomer at UC Berkley, told BBC News that he and his colleagues were able to detect “different zones, turbulent features, vortices – even the Great Red Spot” using the VLA, which was recently upgraded with a more instrument that enabled them to better detect and analyze radio emissions being given off by planets and other objects.

The team used a special technique that counters the so-called smearing effect that researchers typically see when studying a quickly-rotating body such as Jupiter, a planet with a 10-hour long day, the UK media outlet added. The combination of technique and technology made it possible for the Berkley-led team to collected detailed information about the various weather systems that exist beneath the cloud tops on Jupiter.

According to de Pater and her colleagues, their radio map shows ammonia-rich gases rising and forming the planet’s upper layer of clouds: an ammonium hydrosulfide cloud with temperatures of minus 100 degrees Fahrenheit (200 Kelvin) and an ammonia-ice cloud that roughly minus 170 degrees Fahrenheit (160 Kelvin). Both can easily be seen from Earth using optical telescopes.

Furthermore, the radio map also shows air that is low in ammonia content falling towards the planet’s surface, not unlike how drier air descents from above Earth’s cloud layers. It also shows that hotspots (named because they appear to be bright in radio and thermal infrared images) are ammonia-poor regions that circle around the planet just north of the equator. Located in between these hotspots are the ammonia rich upwellings that carry the gas from deep within the planet.

“All told, there is a wealth of information about the structure of Jupiter’s atmosphere in these new VLA images,” de Pater told BBC News. “We hope to resolve a number of outstanding questions with these and future studies using similar techniques,” the professor added, noting that she and her colleagues hope to conduct similar observations of the atmospheres around the gas giants Saturn and Uranus in the near future.